At Apple’s flagship Worldwide Developers Conference (WWDC) keynote this morning, Steve Jobs had to more or less demand that attendees disable their MiFis and similar devices, because the sheer volume of unique Wi-Fi networks was preventing the proper functioning of the iPhone 4 for demonstration purposes. … 527 Wi-Fi hotspots were in operation in the keynote address, most of them MiFi, and over 1,100 devices connected among those and other shared Wi-Fi networks.

All the people in the audience with their own MiFi devices creating a 5-connection hotspot, is like having 527 radio station transmitting towers in the same room. That doesn’t happen with radio station towers because that radio frequency is regulated – each station must obtain a license that doesn’t overlap any other station’s license. Not so with 2.4 GHz Wi-Fi which is unregulated. Even just a few overlapping Wi-Fi hotspots creates RF Interference, let alone 527!

Coach Connect’s busy Wi-Fi hotspot in 2005 created RF Interference with user devices on one network.